Bruno Mars hosted and performed on this weekend's episode of "Saturday Night Live."Photo: NBC

The insecurities poured out of Bruno Mars.

He stuffed his hands in his pockets. He grabbed for an imaginary blazer button. The singer’s voice wavered as he delivered the monologue on this weekend’s episode of “Saturday Night Live,” a logical reaction for a first-time host without comedy or acting experience.

“I’ve never even done a shampoo commercial before, which is crazy,” he said, pointing to his moppy hair.

So Bruno did what he does best, picking up a microphone and sharing his falsetto with the world.

“Will I someday regret this as a terrible mistake?” he sang. “Can I put aside my fears, can I be like Timberlake?”

No, it wasn’t a mistake, as Bruno – helped by a hard-hitting presidential debate spoof and appearances by Tom Hanks – delivered a Timberlakian episode full of humor and heart.

Bruno also served as the episode’s musical guest, performing songs off of his upcoming album “Unorthodox Jukebox.”

The Grammy darling, 27, has been all over the radio the past few years, churning out hit singles such as “Just the Way You Are” and “Grenade.”

Mars’ singing talents carried a Pandora internet radio power outage skit, one of the show’s highlights. With the site’s music channels unable to stream, the Pandora crew relies on an intern named Devin (Mars) to impersonate popular music acts.

First was Green Day – with Devin screaming gibberish into the microphone, mimicking lead singer Billie Joe Armstrong on “Basket Case.”

Aerosmith followed. Then Katy Perry, “mid-Firework.” Justin Bieber, for a swanky version of “Boyfriend.”

Mars lost composure during his Louis Armstrong impression, a moment of humor amid the music.

The Michael Jackson channel was last – a chance for Mars to emulate one of his musical inspirations.

“I can only do Michael if I have the glove,” he said.

So a gloved Devin shined on “Billie Jean” – until the user skipped the song.

“Who the hell skips Billie Jean?” the boss asks.

Next was “Man in the Mirror.” Another skip. Wha??

Mars sang “Smooth Criminal” – infamous tilt and all, filling the song with nonsense words before another skip.

“They’re out of skips,” the boss said. “Take us home Devin.”

So Mars sang “Beat It” with a background chorus of Pandora employees, the musical output too much for young Devin – but a great way to showcase the host’s talents.

The show opened with a spoof of Tuesday’s heated presidential debate, with SNL’s Mitt Romney (Sudeikis) and President Obama (Jay Pharoah) threatening and interrupting each other throughout.

One of the funniest moments involved Mitt’s son Tagg offering to punch out Obama, a play off of Tagg’s comments in a radio interview that he “wanted to take a swing” at the president.

“Let me have him dad,” Tagg said.

“Sit down, Tagg. Not right now,” Romney responded.

Moderator Candy Crowley (Aidy Bryant) tried to keep the peace.

“Gentlemen, really, this is so inappropriate,” she said.

But the attacks and insults continued as undecided voters peppered the candidates with questions.

The final question came from a “Saturday Night Live” regular – Hanks, fresh from his potty-mouthed Friday appearance on “Good Morning America.” Hanks’ character fumbled with his reading glasses and unfurled the world’s tightest-folded piece of paper to share his question, “which came from a brain-trust of my friends from Global Telecom Supply.”

The question? “Libya,” which sent Romney on an ill-fated effort to correct the President.

“I am willing to bet here and now that you have never in your life even once used the phrase ‘terrorist act,’” Romney said.

“Get the transcript,” Obama said, gesturing to Crowley. “Get ‘em.”

“Governor, he has in fact used the phrase ‘terrorist act,’” Bryant’s Crowley said, a dejected Romney pleading.

Pharoah’s Obama stepped beside Romney then dropped the microphone, hopping away, brushing off his shoulders and bobbing in celebration.

Hanks also appeared in a later-episode skit showing a girlfriend and boyfriend on a haunted ride. The segment involved the couple’s carriage breaking down near a display of animatronic robots.

Everything was fine until the robots started smoking and threatening the riders with chainsaws and knives.

The threats – especially Hanks’ robot, chopping the air with garden shears – scared off the boy (Pharoah). But the girl (Vanessa Bayer) remained inside the car so Hanks hopped in.

“I know I should be scared, but you have a very likeable face,” she said.

“I get that a lot,” he said, clawing at the woman’s chest.

Cast member Taran Killam shined in his spoofs of Brad Pitt’s black and white Chanel ads.

“I’m sorry, is there really no script?” he asked. “I’ve been talking for two hours straight, and I’m starting to sound insane.”

Bill Hader’s Stefon character appeared during Weekend Update to discuss popular Halloween options for New Yorkers. Evidently his dog is named Bark Ruffalo, a play on the “Avengers” actor’s name.

The episode reached a poignant moment with its “sad mouse” short, a commentary on heartbreak and love showing a lovelorn Bruno Mars in a mouse costume floundering through Times Square. The segment was haunting and powerful, the type of thing “Saturday Night Live” used to do with its Schillervision shorts in the 1970s and 1980s.

At the end of the clip, the mouse connected with a woman in a lizard outfit and the pair walked away together – the insecurities gone for the man inside the mouse costume.